CN102569836A - Preparation method of quadruple inorganic molten salt electrolyte - Google Patents

Abstract

The invention relates to a preparation method of a quadruple inorganic molten salt electrolyte. The preparation method comprises the following steps of: (1) weighing LiBr, KBr, CsBr and LiI; (2) placing a drug in a crucible furnace; (3) charging argon gas or nitrogen gas into the crucible in the step (2) and roasting for 1-10 hours; (4) after stirring into electrolyte melt by a quartz rod, taking out of the crucible, quickly pouring the electrolyte melt on a stainless steel plate, and cooling in a glove box protected by the argon gas or nitrogen gas to change the melt into blocky melt electrolyte; and (5) grinding the blocky melt electrolyte into powder to obtain the quadruple inorganic molten salt electrolyte. According to the preparation method, the electrolyte is LiBr-KBr-CsBr-LiI, the melting point is only 236.4 DEG C, the melting heat is 32.3 J/g, the conductivity is greater than 0.1 S/cm, the effective working temperature zone of a thermal cell can be extended from 400-600 DEG C to 250-600 DEG C, and the effective temperature zone is increased by 150 DEG C.

Description

A kind of preparation method of four-component inorganic molten salt electrolyte

technical field

The invention belongs to the technical field of electrochemistry, in particular to a preparation method of a four-component inorganic molten salt electrolyte.

Background technique

Thermal battery is a reserve primary battery using solid inorganic salt as electrolyte, which has the characteristics of high stability and reliability and long storage life. At room temperature, the solid inorganic salt electrolyte is non-conductive, and the inorganic salt electrolyte in a molten state after being heated by the heating material has high ion conductivity. At this time, the single battery can output energy to the outside.

After activation, the electrical performance characteristics of a thermal battery depend on several factors such as the electrochemical system of the single cell, as well as the structure of the battery. Once the thermal battery is activated, as long as the electrolyte remains molten, the thermal battery will be in operation until the active material participating in the reaction is exhausted. On the other hand, even if the active material is in excess, the thermal battery will stop working due to the re-solidification of the electrolyte due to the loss of heat inside the thermal battery.

Therefore, after activation, the following two basic conditions must be met to ensure that the thermal battery can work normally: (1) suitable battery cell electrode materials and sufficient quantities of negative and positive electrode materials; (2) the shape of the entire battery, and The type and amount of insulation used therein.

Thermal batteries are specially designed to meet specific electrical properties. These specific properties include not only output voltage, output current, working life after activation, activation time, etc.; but also include storage environment conditions, activation working environment conditions, assembly and fixing methods, battery surface temperature, activation method and activation energy, etc. The use of molten salt electrolytes for thermal batteries varies greatly depending on the electrical characteristics required for thermal batteries.

In 2005 Serge Schoeffert studied thermal battery modeling (Serge Schoeffert "Thermal batteries modeling, self-discharge and self-heating"; Journal of PowerSources 142(2005) 361-369). This research mainly uses KCl-LiCl and LiF-LiCl-LiBr inorganic molten salt electrolytes, the purpose is to solve the problem of self-discharge and self-heating.

In 2006, Patrick Masset studied iodide-based thermal battery electrolytes (Patrick Masset; "Iodied-based electrolytes: A promising alternative for thermal batteries"; Journal of Power Sources 160(2006) 688-697). The report mainly studies the two-component, three-component and four-component inorganic molten salt electrolytes. The main binary electrolytes studied are: 55.2% KCl-44.8% LiCl with a melting point of 354 °C, 58.2% LiI-41.8% KI with a melting point of 260 °C, and 14.4% LiCl-85.6% with a melting point of 368 °C. The three-component electrolytes studied mainly include: 9.6% LiF-22% LiCl-68.4% LiBr with a melting point of 443 °C, 0.67% LiF-53.5% LiBr-45.83% KBr with a melting point of 312 °C, and 0.81% LiBr with a melting point of 312 °C. %LiF-56%LiBr-43.18%KBr, 3.2%LiF-13%LiCl-83.8%LiI with a melting point of 341°C, 2.6%LiCl-57.3%LiI-40.1%KI with a melting point of 265°C. The studied quadruple electrolyte is 4.9%LiF-11.2%LiCl-34.9%LiBr-49%LiI with a melting point of 360°C.

It is obvious that the typical operating temperature range of thermal batteries using KCl-LiCl inorganic molten salt electrolyte is 400 ° C to 600 ° C through literature comparison research; the typical operating temperature range of thermal batteries using LiF-LiCl-LiBr inorganic molten salt electrolyte is 500 ℃～600℃. The upper limit of the operating temperature of these two electrolytes cannot exceed the decomposition temperature of the positive electrode material, so in fact the effective operating temperature range of the thermal battery is very narrow, which seriously limits the improvement of the battery discharge time and specific energy and specific power. In addition, under the joint action of dynamic mechanical loads such as high temperature and radial centrifugal force, the metal lithium or alloy contained in the lithium alloy negative electrode material of the thermal battery and its liquefaction are thrown out, causing the thermal battery to short circuit and burn out, endangering the overall device safety.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a four-component inorganic molten salt electrolyte. and application security features, as well as features that extend battery life.

A preparation method of a four-component inorganic molten salt electrolyte of the present invention comprises the following preparation process:

(1) Weigh the medicines whose mass percentage content is: LiCl 10%-15%, LiBr 20%-25%, KBr 12%-20%, CsBr 25%-30%, LiI 10%-33% ;

(2) Put the medicine weighed in (1) into an ordinary resistance crucible furnace whose working temperature zone can reach 1000°C;

(3) Fill the crucible furnace of (2) with argon or nitrogen gas, the temperature in the furnace is 500°C-600°C, and roast for 1h-10h;

(4) After being stirred into an electrolyte melt with a quartz rod, take out the crucible, quickly pour the electrolyte melt on a stainless steel plate and cool it in an argon or nitrogen-protected glove box, and the melt becomes a block electrolyte;

(5) Grinding the cooled bulk molten electrolyte into powder to obtain the four-component inorganic molten salt electrolyte.

Moreover, the powder in (5) is 60 mesh.

Moreover, the stirring time of the quartz rod in (4) is 1 minute.

The advantages and positive effects that the present invention has:

The present invention adopts the four-component inorganic molten salt electrolyte LiBr-KBr-CsBr-LiI, and its melting point is only 236.4°C, which is 115.0°C lower than that of the traditional two-component inorganic molten salt electrolyte KCl-LiCl; its heat of fusion is only 32.3J/ g, only 11.0% of the traditional two-component inorganic molten salt electrolyte KCl-LiCl; the conductivity is greater than 0.1S/cm; the effective working temperature range of the thermal battery can be extended from 400°C-600°C to 250°C-600°C, effectively The temperature zone has increased by 150°C.

Description of drawings

Fig. 1 is that the present invention has the thermal analysis curve diagram of the electrolyte of thermal battery with four component inorganic molten salts;

Fig. 2 is that the present invention has the thermal battery electrolyte conductivity-temperature relation graph of four-component inorganic molten salt;

Fig. 3 is the thermal analysis curve diagram of KCl-LiCl of binary inorganic molten salt electrolyte in the prior art;

Fig. 4 is a graph showing the conductivity-temperature relationship of the binary inorganic molten salt electrolyte KCl-LiCl in the prior art.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and through specific embodiments. The following embodiments are only descriptive, not restrictive, and cannot limit the protection scope of the present invention.

Among the present invention, LiCl, LiBr, KBr, CsBr and LiI all are the analytical pure medicines of chemical market purchase, are five kinds of medicines of required composition with the electronic scale of 0.001g or equivalent weighing apparatus weighing and put into common In the chemical porcelain crucible; the main preparation method is to put the chemical porcelain crucible containing the weighed medicine into an ordinary resistance crucible furnace with a working temperature range up to 1000°C, and bake it in an argon or nitrogen atmosphere at a temperature of 500 In the range of ℃～600℃, the calcination time is controlled at 1h～10h. Use a quartz rod to stir the electrolyte melt to reach the firing time, the stirring time is about 1 minute, then take out the crucible from the furnace, and quickly pour the electrolyte melt on a stainless steel plate and cool it in a glove box protected by argon or nitrogen . Grinding the cooled melt block into 60-mesh powder can obtain the four-component inorganic molten salt electrolyte.

Example

Weigh 22.5g of LiBr, 15.4g of KBr, 27.5g of CsBr and 34.6g of LiI, put them into an ordinary chemical porcelain crucible, and put the chemical porcelain crucible containing the weighed medicine into the working temperature zone to reach 1000 ℃, bake in an argon or nitrogen atmosphere at a temperature of 540°C for 2 hours, then stir the electrolyte melt with a quartz rod for about 1 minute, then take out the crucible from the furnace , and quickly pour the electrolyte melt onto a stainless steel plate and cool it in an argon or nitrogen protected glove box. Grinding the cooled melt block into 60-mesh powder can obtain the four-component inorganic molten salt electrolyte LiBr-KBr-CsBr-LiI.

The SETARAM SETSYS EVOLUTION 16/18 thermogravimetric comprehensive analyzer is used to test the melting point of the four-component inorganic molten salt electrolyte LiBr-KBr-CsBr-LiI, using an Al2O3 crucible, using argon as the analytical atmosphere, and testing at a heating rate of 10°C/min. It has been tested that the electrolyte for thermal batteries with the four-component inorganic molten salt shown in FIG. 1 starts to melt at 236.4° C., and the heat of fusion is 32.3 J/g.

Use a DDS-302B conductivity meter with a measurement range of 100 μS/cm to 2S/cm, and select a platinum black electrode with a conductivity electrode length of 10 for the conductivity test. The conductivity-temperature relationship curve of the electrolyte for thermal batteries with the four-component inorganic molten salt of the present invention shown in FIG. 2 was tested.

comparative example

Purchasing analytically pure pharmaceuticals KCl and LiCl from the chemical market. 55.2g of KCl and 44.8g of LiCl were put into an ordinary chemical porcelain crucible. Put the chemical porcelain crucible containing the weighed medicine into an ordinary resistance crucible furnace whose working temperature can reach 1000°C, and bake in an air atmosphere at a firing temperature of 540°C and a firing time of 2 hours. After roasting for 2 hours, stir the electrolyte melt with a quartz rod for about 1 minute, then take out the crucible from the furnace, and quickly pour the electrolyte melt on a stainless steel plate to cool in an ordinary atmospheric environment. Grind the cooled melt block into 60-mesh powder to obtain the binary inorganic molten salt electrolyte KCl-LiCl.

The SETARAM SETSYS EVOLUTION 16/18 thermogravimetric comprehensive analyzer was used to test the melting point of the three-component inorganic molten salt electrolyte KCl-LiCl, using an Al2O3 crucible, the analysis atmosphere was argon, and the heating rate was 10°C/min. After testing, the KCl-LiCl electrolyte starts to melt at 351.4°C, and the heat of fusion is as high as 294.1J/g.

Use a DDS-302B conductivity meter with a measurement range of 100 μS/cm to 2S/cm, and select a platinum black electrode with a conductivity electrode length of 10 for the conductivity test. Accompanying drawing 4 is the conductivity-temperature relation graph of the three-component inorganic molten salt electrolyte KCl-LiCl of the comparative example.

From the above results, it can be seen that since the present invention uses the four-component inorganic molten salt electrolyte LiBr-KBr-CsBr-LiI, the melting point is only 236.4°C, which is 115.0°C lower than that of the traditional two-component inorganic molten salt electrolyte KCl-LiCl; Its heat of fusion is only 32.3J/g, which is only 11% of the traditional two-component inorganic molten salt electrolyte KCl-LiCl; the conductivity is greater than 0.1S/cm; the effective working temperature range of the thermal battery can be extended from 400°C-600°C to From 250°C to 600°C, the effective temperature range increases by 150°C.

Claims (3)

1. a preparation method of four-component inorganic molten salt electrolyte, is characterized in that: comprise following preparation process: (1) The mass percentage content of weighing is: LiBr is 20%～25%, KBr is 12%～18%, CsBr is 25%～30%, LiI is 27%～43% medicine; (2) Put the medicine weighed in (1) into an ordinary resistance crucible furnace whose working temperature zone can reach 1000°C; (3) Fill the crucible furnace of (2) with argon or nitrogen gas, the temperature in the furnace is 500°C-600°C, and roast for 1h-10h; (4) After being stirred into an electrolyte melt with a quartz rod, take out the crucible, quickly pour the electrolyte melt on a stainless steel plate and cool it in an argon or nitrogen-protected glove box, and the melt becomes a block electrolyte; (5) Grinding the cooled bulk molten electrolyte into powder to obtain the four-component inorganic molten salt electrolyte. 2. The preparation method of the four-component inorganic molten salt electrolyte according to claim 1, characterized in that: the powder in (5) is 60 mesh. 3. The preparation method of the four-component inorganic molten salt electrolyte according to claim 1, characterized in that: the stirring time of the quartz rod in (4) is 1 minute.

Images